Apparatus for screening paper pulp



11, 1944- E. cowLEs APPARATUS FOR SCREENING PAPER PULP 2 Sheeis-Sheet 1 Filed April ll, 1940 Il UIMM [IMM i 'I'NVFETOR l Y y,

f /ATTORNEY Jan.4 11, 1944.

|:. c :owLEs APPARATUS FOR SCREENING PAPER PULP 2 sheds-sheet 2 Filed April 1l, 1940 l 1N NToR mais im. ii, i944 i i 2,338,904

UNiTED sTATi-:s rATENT OFFICE r APPARATUS FOR SCREENING PAPER PULP Edwin Cowles, Cayuga. N. Y., assignor to The Cowles Company, Princeton, N. J., a corporation o! New Jersey Application April 11, 1940, serial No. 329,031

' a 'claims (ci. en -32) This invention relates to apparatus for screening paper pulp.

It is an object of the invention to provide im proved means for vibrating the screen element,

material such as asphalt or pitch which prevents penetration oi' the Water in which the magnet units are immersed during operation of the apparatus. A copious amount of asphalt is used to and improved means for supporting said screen lill all the intersties between the conductor wires element, whereby improved screening efficiency and t mi any Spaces remaining in the TGUQhS and improved accessibility for cleaning and reafter assembling the @Oils thereinn Furthermore, pair are secured. the bottom of the trough 8 and the spaces at the Other objects and advantages of the invention ends of the trough 8, beyond the members and will appear hereinafter. 1m ii, as Well as the side spaces are filled. However, A preferred embodiment of the invention sethe Spa@ between the trough members 5 and 5 lected for purposes of illustration is shown in the is not iled, but is left open to provide a' groove accompanying drawings, m which, for the reception of a strip I0 of relatively soft Figure 1 is a, tgp plan View, resilient material such as sponge rubber, for ex- Figure 2 is a section on the line 2--2 of Fig- 15 empl@- ure 3, l The upper surfaces of the strips i8 engage and Figure 3 is a longitudinal section on. the line Support the screen 3 and additional strips ll 0f 3--3 of Figure l.v similar resilient material are mounted along the Figure i is a detail sectional view of one of the side and end walls oi' the container l to engage lelectro-magnets. and support the outside edges or rim of the Figure 5 is a top pian View 0f one end of one screen, along the entire periphery thereof. Thus, 0i: the eieciirmegnetg, when the electro-magnets are energized, they Referring to the drawings, the apparatus comtend to draw the screen down to slightly comprises a container i of any suitable shape, herein a press the resilient strips IG and.A ii, and when shown in elongated rectangular form, in which is the magnets are thereafter deenergized, the remounted a. screen element 2 of iron .or other suitsilience or the strips i0 and il pushes the screen able magnetic material. up again. l

According to the present invention, it is pro- In conventional paper pulp screens it is necposedto vibrate the screen element magnetically, essary to use a fairly thick and heavy screen and to apply the magnetic torce directly to the element in order to secure the required rigidity, screen, using the screen as an armature. Acand because of the thickness required the screen cordingly, a plurality oi electro-magnets 3 are apertures are usually milled slots which'are not mounted in said container immediately below the only very expensive, but also seriously limit the screen element, but spaced therefrom. in the capacity ci the screen because of the relatively preferred embodiment illustrated, the said elecwide spacing required between slots.` According tro-magnets are elongated in form and extend to the present invention, however, because of the lengthwise of the container from one end of the novel method or vibration and support of they screen to the other. Four such magnet uni'is are screen element, it may be made of very light. ma-

distributed at intervals across the container, so terial. -For example, a screen plate having a that substantially the entire area of the screen 40 .thickness of .640" has been found entirely adel1 is within the eiective field .of the magnets. quete and ordinary drilled perforations having a The construction of the magnet units is illusdiameter substantially equal to the thickness of trated in Figures 4 and 5. Each unit comprises the plate have been found satisfactory. Such a pair of U-shaped trough members 5 and 8, perforations may be closely spaced and provide preferably of iron, laid parallel to each other, unusually high capacity. but spaced a short distance apart. A coil of con- The magnet units may be energized intermitductor wire 1 is laid in said trough members, each tently to vibrate the screen element by utilizing winding of the coil extending lengthwise along any of the well known electrical devices for supone ot said trough members to the end thereof,v plying intermittent or pulsating current. For exthen around the end, then lengthwise of the ample, a relatively low frequency (60cycles or other trough member in the opposite direction, less) alternating current may be used. or interand so en mittent direct current may be used.

The trough members l and 6 are mounted in a In the operation of the apparatus raw stock is larger trough 8, and the conductor wires are owed through inlet opening I5 to a head box sealed in by a covering 9 of suitable protective 66 I6 having a dam l'l over which the stock flows cleaning andy repair.

onto the screen, being distributed by the dam over the entire width of the screen. Acceptable stock passes through the screen perforations, owlng back along the bottom of the container to the screen to assist-in the separation of good stock v from tailings, and to Wash the tailings toward` the outlet opening 22.

Since the ow of stock through the screen element and the magnetic force both tend to hold said resilient means, additional resilient means in abutting contact with the same face of the screen and distributed at spaced intervals over the screen against the resilient strips Il, an adei quate seal is provided at the edges of the screen to prevent flow of stock around the edges of the screen and between the screen and said strips. However, sincev no mechanical devices are required to hold the screen in place, it may be easily lifted out of the container to permit inspection,

It will be understood that the invention may be variously modified and embodied Within the scope of the subjoined claims.

I claim as my invention:

1. In an apparatus for screening paper stock, in combination, a screen, resilient means in abutting contact With one face of said screen along the edges of said screen around the entire periphery thereof and sealing the edges of said screen to prevent iiow of stock between said screen and the surface thereof, and means to apply magnetic 'force intermittently to the screen over substantially the entire area thereof to draw said screen uniformly against all of said resilient means to compress the same substantially uniformly throughout the area of the screen.

2. In an apparatus fQr screening paper stock, in combination, a container, a screen in said container, resilient means in said container, said resilient means consisting of compressible material in abutting contact with the edges of said screen around the entire periphery thereof and sealing the edges of said screen to prevent ilow of stock between said screen and said `resilient means, vand means for intermittently applying magnetic force directly to said screen to draw said screen against said resilient means to compress the same, said resilient means serving to move said screen in the opposite direction when said magnetic force is interrupted.

3. In an apparatus for screening paper stock, in combination, a container, a screen in said con'- tainer, a plurality of electro-magnets in said container adapted to apply magnetic force directly to said screen, said electro-magnets being'elongated and substantially co-extensive with said screen in one direction and distributed at in tervals across said screen in the other direction, whereby substantially the entire area of said screen is within the effective field of said e1ectromagnets, and the entire area is moved through' substantially equal amplitudes.

' EDWlN COWLES. 

